The present disclosure relates to a shield structure for an electronic apparatus that shields a wiring substrate attached to an electronic apparatus.
Electronic apparatuses that form images on sheets by electrophotography, including, for example, image forming apparatuses such as a copier and a printer, are provided with a plurality of wiring substrates such as a drive system control substrate and an image processing substrate. Noise radiated from electronic components mounted on each of these wiring substrates causes the problem of malfunction of other electronic components.
Therefore, attempts have been made to shield radiation noise by accommodating, in a sealed space in a body frame made of sheet metal, wiring substrates having mounted thereon electronic components that generate radiation noise so as to shield the wiring substrates.
However, accommodating wiring substrates such as a drive system control substrate and an image processing substrate in the sealed space in the body frame is not easy both in terms of structure and cost.
As shown in the sectional view of FIG. 6, in a known conventional shield structure for a wiring substrate, a housing 101 that encloses a wiring substrate 30 having electronic components 31 and 32 mounted thereon is formed by a body 101A supporting the wiring substrate 30 from the underside and a lid portion 101B covering the body 101A from above. In this case, the lid portion 101B is fixed to the body 101A with a plurality of screws 21 disposed at a pitch interval that inhibits noise radiation. Additionally, a plurality of projection-like connecting portions 13 and 23 protruding toward the wiring substrate 30 side are formed in the body 101A and the lid portion 101B, respectively, and the wiring substrate 30 is sandwiched by the connecting portions 13 and 23. This allows the noise generating from the electronic components 31 and 32 to be fed back to the wiring substrate 30 in a small loop, thus preventing a state in which the housing 101 acts as an antenna to radiate noise.